The present invention relates generally to abrading or grinding devices. More particularly, the device of the invention relates to a ceiling vacuum-assisted grinding apparatus for use in surfacing of drywall and concrete ceilings.
Drywall and concrete have now become very popular materials used in the construction of buildings, mainly because of their strength and durability and because molding and casting technology has advanced greatly in recent years. However, in most cases after a concrete structure, such as a ceiling has been cast and the mold removed therefrom, the surface of the concrete ceiling is rough due to inconsistencies in the surface of the molds and indentations formed by the seams between adjacent molds. Thus, it is necessary to dress or smooth poured concrete ceilings by grinding the exposed surfaces of the ceiling. The same is generally true about the drywall ceilings although they require substantially less grinding to smooth the surface.
Although there have been ceiling grinding machines known in the prior art, these machines have been unsatisfactory in various manners. First, typically these grinding machines utilize abrading discs, cups or belts which wear out quickly, necessitating expensive and time consuming replacement, and do not provide a very strong abrading force to the concrete. Additionally, these ceiling grinding machines typically drive the abrading device by means of the flexible cable coupled to an electrical motor. However, this flexible cable is subject to intense frictional forces and therefore wears out quickly. Moreover, the use of single-phase electrical motors to run such abrading devices restricts the device to one rotational speed, thereby reducing the versatility of the device.
Another problem with prior art machines is their poor maneuverability. In most buildings under construction, both plumbing stubs and electrical conduit stubs protrude from the floor approximately 8 to 18 inches above the floor's surface and the prior art grinders have transverse axles and low horizontal framing which are well below the average height of the plumbing and electrical conduit stubs. This obviously causes interference and makes it difficult to maneuver the machine while trying to grind the ceiling above the floor.
A further problem is controlling the apparatus during the grinding operation. In the prior art devices, the grinding mechanism must be manually manipulated against the ceiling by the operator, while the operator moves the entire apparatus over the area to be grinded. This distracts the operator from safely traversing the floor upon which the apparatus is guided and also forces the operator to stand quiet close to the grinding assembly, increasing the chance of injury to the operator from flying concrete chips.
Examples of grinding machines of the prior art can be found in the U.S. Pat. Nos. 2,670,577; 2,755,606; 3,268,935; 3,948,005, and 4,381,911, all of which are incorporated herein by reference in their entirety.
Pole-mounted sanders have also been described in the prior art for the purpose of reaching the ceiling in a manner more convenient then with a hand-held sander. U.S. Pat. No. 4,663,796 describes an exemplary standard pole-mounted sander.
For many years carpenters, sheet-rockers, auto body sanders, tapers, etc. have attempted to cope with the problem of disposing conveniently of the remains of a sanding operation. Of course, a sanding operation typically ends with a large volume of sanding remains in the work area, both on the work surface and in the air. One of the common methods of disposing of the sanding remains related to a separate, after-operation vacuuming process for the work surface and the floor around the work surface. For this purpose, a large variety of “industrial-strength” vacuum system have been designed and developed. After all, the vacuum system had to cope with more then the usual dust and the like found in the home environment. Most importantly, such “industrial-strength” vacuum system did a fine job on the work surface and other proximate surfaces, but did nothing for the sanding remains spread throughout the air in the work place. Commonly, this subjected the person doing the sanding to lung and other health hazards, both during the sanding operation and thereafter.
Dust evacuation has been finally accomplished by various powered or manual sanders equipped with vacuum and suction means. More recently, inventors such as Shaw, U.S. Pat. No. 4,759,155 (incorporated herein in its entirety by reference) have developed methods and apparatus, which involve a plurality of holes in a sanding plate underlying the sand paper, which was designed with a porous material. In this way, the sanding remains are vacuumed during the sanding operation into a vacuum plenum, and this prevents, for the most parts, the dispersing of sanding remains into the air of the work place. However, the pattern of openings to the plenum and vacuum system in the underlying plate prove less efficient than it could be in gathering all of the sanding remains as the sanding operation proceeds. Also, the plenum tends to clog up.
In the U.S. Pat. No. 4,765,099 by Yanner there is disclosed a sanding and dust collecting apparatus. A housing assembly is attachable to and supported by a pneumatic sander. An impeller blade creates a vortex-like suction and thereby propels the particulate matter generated by the sander towards a collection bag.
Next is U.S. Pat. No. 4,937,984 issued to Thomas F. Taranto. This patent discloses a vacuum sander wherein a housing that forms a vacuum manifold communicating with an abrasive sheet at one end, the sheet being supported by an air permeable foam pad. Both a hand-held and a handle-held embodiment are described and it is explained that the source of the vacuum could be a standard household vacuum cleaner or the like.
U.S. Pat. No. 4,680,895 by Roestenberg discloses a block sander vacuum wherein a plurality of ports are disposed proximate a removably attached abrasive surface. These ports are connected to a coupling means for connection with a conventional vacuum cleaner. Additionally, on opposite sides of the body of the device are disposed depending skirts to aid in the collection and directing of the particulate matter generated by the sanding process.
Next in this discussion is U.S. Pat. No. 4,779,385 by Reiter. A gypsum board sanding apparatus is described wherein a paddle adapted to support a sheet of sandpaper includes a plurality of apertures both through and about it to allow for the passage of air and dust particles into a plenum that is connected to a conventional vacuum cleaner.
U.S. Pat. No. 4,964,243 (incorporated herein by reference in its entirety) also by Reiter discloses a vacuum pole sander. A sanding head includes a number of pedestals for supporting the abrasive material. The head member is configured to be attached to a universal joint and, to a pole for sanding hard to reach areas.
U.S. Pat. Nos. 5,193,313; 5,540,616; 5,624,305; and 6,468,141 (incorporated herein by reference in their entirety) describe various other useful variations of vacuum-assisted sanders mounted on a pole and having a universal swiveling joint between the sanding pad and the pole. U.S. Pat. No. 689,464, shows a power brush supported by a central pole.
Finally, U.S. Pat. No. 4,204,292 shows a portable powered scrubbing tool with vacuum assist and supported by two supporting poles: the main pole and the auxiliary pole extending from the mid portion of the main pole. It is adapted to be held by the operator using both hands.
Despite the above described advances in the sanding device, the need still exists for a low weight vacuum sander allowing sanding of a ceiling with minimal effort, while providing for excellent maneuverability and for effective removal of the dust and sand particles.